This invention relates to 1-substituted-pen-2-em-3-carboxylic acids(I) and their pharmaceutically acceptable salts and esters which are useful as antibiotics. This invention also relates to a process for preparing such compounds, (I): ##STR2## wherein R.sup.1 and R.sup.2 are selected from the group consisting of substituted and unsubstituted: loweralkyl having from 1-6 carbon atoms; aralkyl such as phenyloweralkyl; aryl such as phenyl; cycloalkyl having from 3-6 carbon atoms; and cycloalkylalkyl having 1-3 carbon atoms in the alkyl moiety and 3-6 carbon atoms in the ring; additionally, R.sup.1 and R.sup.2 may be joined together to form a spiro cyclic substituent at ring position number 1. Wherein said ring or chain substituents on R.sup.1 and R.sup.2 are selected from the group consisting of halo, such as chloro, bromo, fluoro and iodo, hydroxyl, amino, mono-, di-, and trialkylamino wherein the alkyl moiety has 1-6 carbon atoms; carboxyl, carbamoyl, amidino, guanidino, ureido, and the like.
There is a continuing need for new antibiotics. For unfortunately, there is no static effectiveness of any given antibiotic because continued wide scale usage selectively gives rise to resistant strains of pathogens. In addition, the new antibiotics suffer from the disadvantage of being effective only against certain types of microorganisms. Accordingly, the search for new antibiotics continues.
Thus, it is an objection of the present invention to provide a novel class of antibiotics (I) which are useful in animal and human therapy and in inanimate systems. These antibiotics are active against a broad range of pathogens which representatively include both gram positive bacteria such as S. aureus, Strep. pyrogenes, and B. subtilis and gram negative bacteria such as E. coli, Proteus morganii, Serratia, Pseudomonas and Klebsiella.
Further objects of this invention are to provide chemical processes for the preparation of such antibiotics and their non-toxic pharmaceutically acceptable salts and ester; pharmaceutical compositions comprising such antibiotics; and to provide methods of treatment comprising administering such antibiotics and compositions when an antibiotic effect is indicated.